Usually, adhesive papers for copying prepared by laminating an overlying sheet with a release sheet so that an adhesive layer coated on the bottom surface of said overlying sheet is in contact with the releasing surface of said release sheet are subjected on the surface of the overlying sheet to copying with a copying machine, the release sheet is then peeled off therefrom and the copied overlying sheet is applied to a desired place.
In preparing adhesive papers for copying having the structure as mentioned above, acrylic or rubber adhesives have heretofore been used to form adhesive layers to be coated on the bottom surface of the overlying sheet of said adhesive papers. The adhesive papers for copying prepared by using such adhesives, however, involved such a serious problem that when they are brought into contact with a cylindrical photoreceptor of copying machine, the adhesives sometimes squeeze out of the edge face of the adhesive papers to contact with the cylindrical photoreceptor, with the result that the cylindrical photoreceptor of the copying machine is contaminated with the squeezed adhesives. In addition thereto, there was also such a problem that the adhesive Papers for copying of the type undergo heating at the time of fixing the toner, and if the adhesives used in said adhesive papers are low in heat resistance, they sometimes squeeze out of the edge face of the adhesive papers, Whereby the toner fixing equipment comes to be contaminated with the squeezed adhesives.
In order to solve the problems associated with adhesive papers for copying of the prior art mentioned above, various improvements have been proposed. For instance, Japanese Laid-Open-to-Public Publn. No. 159874/1984 discloses adhesive papers for copying which are characterized in that the edge face of the adhesive papers is provided with a coating layer to inhibit squeeze-out of the adhesive from the adhesive papers, said coating layer comprising a cellulose derivative coating such as nitrocellulose, and acetylcellulose, an organic solvent based synthetic resin coating such as thermosetting acrylic resin, and phenol-formaldehyde resin, or a water based synthetic resin coating such as vinyl acetate resin. and styrenebutadiene copolymer.
In the adhesive papers for copying disclosed in Japanese Laid-Open-to-public publn. No. 159874/1984 referred to above, however, there was involved such a problem that the coating applied to the edge face of the adhesive papers sometimes permeates into the overlying sheet, adhesive layer and release sheet, and hence protection of the edge face becomes insufficient, thereby the adhesive of the adhesive layer of the adhesive papers squeezes out in some cases. Furthermore, another problem also involved therein was such that the overlaying sheet and release sheet come to curl by application of heat when the coating applied to the edge face of the adhesive papers is cured by heating.
On one hand, although they are not adhesive papers for copying, disclosed in Japanese Patent Publication No. 10353/1975 are lap winding adhesive tapes which are characterized in that the edge face of the adhesive tapes is coated with an organic solvent containing a photocrosslinking sensitizer, photochemical crosslinking agent and vinyl type high molecular compound, and the coating formed on the edge face is cured by irradiation, thereby inhibiting squeeze out of the adhesive from the edge face of the adhesive tapes. However, if this technique is intended to apply to adhesive papers for copying, there was such a problem that the organic solvent used permeates into the overlying sheet or release sheet of the adhesive papers, whereby the overlying sheet or release sheet undergoes curling and, at the same time, an environmental pollution is brought about by the use of the organic solvents.
According to experiments conducted by the present inventors, it has been found that adhesive papers for copying having a radiation-induced polymer layer formed on the edge face of the adhesive papers by irradiating radiation polymerizable compounds such as epoxy compounds are fed to a copying machine, whereupon the radiation-induced polymer layer is broken in some cases and falls off from the adhesive papers when the adhesive papers are fed to a copying machine and pressed against a cylindrical photoreceptor, thereby the cylindrical photoreceptor is contaminated with the fallen radiation-induced polymer layer in certain cases.
With the view of solving such problems as referred to above at a single stroke, the present inventors conducted extensive researches and eventually have found that said problems can be solved at once by providing at least one edge face of adhesive papers for copying with a resin layer formed by using radiation polymerizable compositions capable of providing a resin layer having a glass transition temperature prescribed herein, but without using any solvents. Thus, the present invention has been accomplished